The effect of 3-cyclohexylamino-propionitrile and aminocyclohexane on the behaviour steel in HCl solution

Inhibitory effect of some new synthesized and analyzed aminocyclohexane compounds, namely, 3-cyclohexylaminopropionitrile (P1) and aminocyclohexane (P2) respectively; on corrosion of steel in 1M HCl solution has been studied using weight loss measurements and electrochemical technique polarization methods. The results obtained reveal that these compounds are efficient inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration and reaches 90 % for P1 at 10-3 M. Potentiodynamic polarisation studies clearly reveal that P1 and P2 acts cathodic inhibitors without change of the mechanism of hydrogen evolution. The temperature effect on the corrosion behaviour of iron in 1 M HCl without and with the inhibitors at 10-3 M was studied in the temperature range from 313 to 353 K. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that variation of inhibition with structure of the inhibitor may be explained in terms of electronic properties. The inhibitors were adsorbed on the iron surface according to the Langmuir adsorption isotherm model at different temperature. From the adsorption isotherm some thermodynamic data for the adsorption process (K and DG°ads) are calculated and discussed.